Method of making sheet metal piston rings



1943- T. A. BOWERS METHOD OF MAKING SHEET METAL PISTON RINGS Filed March 28, 1940 N I l/ 4 Shgets-Sheet 1 INVENTOR" I BY. I

ATTORNEY Feb. 23, 1943. T. A. BOWERS 2,311,729

-METHOD OF MAKING SHEET METAL PISTON RINGS Filed March 28, 1940 4 Sheets-Shet 2 --lNVENTOR BY 60mm ATTORNEY 1 1943- T. A. BOWERS T ,311,729

METHOD OF MAKING SHEET METAL PISTON RINGS F iled March 28, 1940 4 Sheets-Sheet s INVENTOR' ATTORNEY Feb-$23; 1 1'. A. BOWERS METHOD OF MAKING SHEET METAL PISTON RINGS File d March 28,- 1940 4 Sh eets-She et 4 ATTORNEY Patented Feb. 23, 1943 METHOD OF MAKING SHEET METAL PISTON ames Thomas A. Bowers, Boston, Mass., assignor to Power Research Corporation, Boston, Mass, a corporation of Massachusetts Application March 28, 1940, Serial No. 326,341

1 Claim. .(01. 29156.6)-

This invention relatesto piston rings and more especially to methods of manufacturing oil control piston rings, and is a continuation in part of my co-pending applications Ser. No. 268,721, filed April 19, 1939, and Ser. No. 276,503, filed May 31, 1939.

In the manufacture of piston rings of the oil control type, it is customary to provide, among other features, relieved circumferential edges for more efliciently scraping oil from the wall of a cylinder. Such edges are attained by various methods, as by recessing solid rings, by utilizing a plurality of thin steel rings supported on a spacing ring, or in other ways. The solid rings fail when their recessed portions become filled up and clogged with carbon.- The steel ring A chief object of the invention is to improve methods of making piston rings and to devise methods of incorporating in a ring body circumferential portions which extend from the ring to constitute oil scraping edges, and comprise a novel oil control piston ring. The invention also aims to provide methods of making piston rings from sheet materials by which desirable ring structures and ring functions are developed, and to indicate procedures whichare adapted to being carried out with well known tool machinery, thereby making the manufacture of piston rings cheaper and more efficient.

Attainment of these and other objects of the invention will appear in the following description of the drawings and the discussion relating Fig. 4 is a perspective view illustrating a furr ther step in the method referred to.

Fig. 5 is a fragmentary plan view of the finished ring as viewed from above.

Fig. 6 is a plan view illustrating the completed ring.

Fig. 7 is a modified type of piston ring material and also illustrates a modification in the process.

Figs. 8-13, inclusive, illustrate another modification in methods of forming sheet metal to comprise a piston ring.

Figs. 14-19, inclusive, illustrate another modifled method of forming sheet metal into a piston ring.

Figs. 20-24, inclusive, illustrate still another modified method.

Figs. 25 and 26 illustrate another general type of method of making rings; and

Figs. 27 and 28, inclusive, illustrate a modification of the method indicated in Figs. '25. and 26.

Referring in detail to the drawings, there have been illustrated a number of methods of making piston rings particularly directed .to use of the rings as oil control members. 01 the procedures indicated, Figs. 1-6 relate to one general type of method; Figs. 7-24, inclusive, indicate modifications thereof; and Figs. 25-28, inclusive, illustrate another general type of method of making rings. I

In the construction indicatedin Figs. 1-6, inclusive, numeral I denotes a strip of sheet material employed in making the rings of the invention. The sheet material is of a resilient nature I and may be spring steel, alloy or other metal or suitable substance. In accordance with the invention, the strip 1 is formed in some suitable manner to provide segments or crown portions which are disposed in contiguous relation to one another to form a novel ring body. As illustrated in Figs. 2 and 3, the strip is punched to provide openings 2 extending generally transversely within its edges, thereby forming transverse web portions 3. At the edges of the strip are additional cuts or slits 4 and 5 which, along either edge, connect with every other opening 2.

;;:-I It will be noted that the cuts 4 along one edge are staggered with relation to the cuts 5 along the opposite edge, with the result that there are provided segments or crown portions 6 and l occurring also in staggered relationship at opposite edges of the strip. The formed material is folded over in a direction longitudinally of the stripto provide a generally U-shaped member, or a member vof some other open formation, in which the segments 6 of one edge of the strip occur in spaced relation to the segments I- of the opposite edge, as shown forexample in Fig. 4. This provides a length of material which may be formed into an annular body as indicated in Fig. 5. A length of the material suitable for constiby conventional cutting or shearing dies, and the folding carried out with press or rolling mechanism. Forming a straight length of folded material into a circular body can be eifected in several ways, one example of which is to force a length of the material through an annular channel or die.

In the construction indicated there is provided an annular supporting structure comprising the web portions 3 folded over and forming an inner periphery of the ring. In the folded position of the sheet material, the openings 2 extend both radially and vertically of the ring and provide for the folded webs being spaced apart in compressible relation to one another.

Extending radially outward from the supporting structure are the two series of segments 6 and I, the segments of each series being disposed in contiguous relation to one another and the two series forming respectively upper and lower spaced-apart circumferential edges. The cuts'or openings 4 and 5, in the folded position of the strip, extend radially and provide for adjacent segments in each of the above mentioned edges also being spaced apart in compressible relation to one another.

The openings 4 of the top circumferential edge occur in staggered relation with respect to the openings 5 of the bottom circumferential edge so that contact with a cylinder wall not effected by one circumferential edge will be taken care of by the other edge. Also, the openings 4 and 5 connect with alternate openings 2 to form continuous passages extending radially of the ring.

An important feature of the method described consists in arranging separately formed segments or ring portions in contiguous relation to one another to form oil scraping edges incorporated in a unitary piston ring structure and extending therefrom in spaced-apart relation to form a reservoir between them, through which oil collected by the edges may be passed to be returned to the crankcase. It has been found that peripheral edges made up of contiguously arranged segments are effective in taking the place of thin edges such as those presented by thin steel C-type rings or other ring structures. Also, when coupled with a circumferentially extensible and contractible supporting structure, such composite or sectional edges are more efficient than theearlier rings noted. There is attained exceptionally good contact of the ring with worn cylinders and highly efiicient oil metering.

Another feature of the method referred to consists in novel land surfaces or sealing surfaces" which provide for satisfactory seating or sealing of a ring in its groove. This is effected by forming the segments 6 and 1 of a size such that when they are arranged beside one another they may comprise a surface large enough for sealing purposes. The segments are also so formed and arranged by the method described that they may constitute only a part of the radial width of the ring, and may occur at one side of a ring supporting structure. With this reduced sealing surface construction, it becomes possible to form a light, efficient ring which at its supporting portions may be of an open character adapted to facilitating rapid passage of oil therethrough. Also, by introducing construction of satisfactory sealing surfaces from separate segments or ringforming portions, and satisfactory peripheral oil scraping edges from such portions, various composite piston ring constructions and methods of manufacture are possible.

A still further feature of the method referred to consists in the development of extensible and contractible character in the ring. This is effected in novel fashion-by cuts or openings 2, I and 5 arranged in overlapping relation whereby intervening sections or portions of the cut material may be bent or flexed toward one another. By this means there is effected an extensible and compressible element which is adapted to be formed into an annular body and thereafter to present circumferential extensibility and compressibility. In developing extensibility in this way in an annular body, a preferred result may be obtained by making those cuts or openings which are to occur at the inner periphery of the body larger than the openings which are to occur at the outer periphery of the body, as for example has been done with respect to openings 2 on the one hand, and 4 and 5 on the other. This improves the range of compressibility and extensibility which are available from the ring.

In addition to the circumferential compressibility and extensibility noted, there is further provided novel vertical resiliency of the circum- "ferential edges with relation to one another.

This results from the open or U-shaped type of folded construction described and may be utilized to engage a ring in a piston groove for preventing slapping of the ring in its groove and achieving other desirable purposes such as holding the ring in a-sealed position at both sides of its groove at'all points in the stroke of the piston.

Another advantage of the ring described is the reduction in surfaces upon which carbon can form to obstruct passage of oil through the ring. It is pointed out that in substantially all oil rings special passages are provided to repass oil through a piston into an adjacent crankcase. Such openings of any appreciable size occurring in a ring body tend to become clogged with carbon. Carbonization takes place in two ways; first, in the form of a thick soft body which develops rather quickly; and second, in the form of a hard scaly mass which is formed after longer periods of ring operation. The ring of the invention provides oil passages comprised by the openings 2 which resist formation of either type of carbon. The openings 2 are designed to provide large oil passageways and yet there is relatively little surface of the ring material around the openings upon which carbon can collect or form. It is pointed out that in order for the openings to be closed up, carbon must form on the thin edges of the sheet material and such edges provide very poor supporting surfaces for any appreciable thickness of carbon to become firmly established thereon. Also, the flexing of the ring further avoids carbon formation at the edges referred to, as well as in the openings 4 and 5.

In operation the ring functions as a gapless ring with its ends adapted to abut one another. By its circumferential resiliency and resulting extensibility, the ring completely engages the wall of a cylinder, conforming to any non-uniformity or worn areas in the cylinder, and exerting a substantially un form pressure at all points therealong. It should be noted that the extensible character of the ring is attained without the use of expander members disposed between the back of the ring and its ring groove. As a result there is less transfer of piston slap," and a reduction of wear ordinarily developing from such piston slap.

With reference to specific operation of the ring structure as an oil metering member, it is pointed out that the two series of segments 6 and I are each contiguously arranged to constitute substantially continuous circumferential surfaces by which the ring may form a satisfactory seal against a top or bottom side of a piston groove for preventing passage of oil thereby. The thickness of the sheet metal may be varied to provide varying thickness of the oil scraping edges, and the interstices are adapted to continually pass oil radially through the ring. By the location of the relatively large openings 2 extending well out toward the circumferential surfaces made up of the segments 6 and 1, oil collected by these segments may rapidly be passed over the ring into the piston groove and then down into the crankcase.

Various advantages are present in connection with the piston ring construction illustrated in Figs. 1-6, inclusive. There is provided a onepiece ring which is adapted'to be conveniently handled and quickly assembled in a piston groove. The ring is provided with a novel compressible and extensible character, rendering it particularly adapted to conforming to worn'or irregular cylinder surfaces. There are also provided thin oil scraping edges of a character closely simulatingthe edges of separate steel c-type rings or other forms of oil rings. The entire structure is adapted to be formed of a tough, thin material, such as steel, of which only relatively small amounts are required, which results in a light, durable ring. In addition, the use of materials of the character indicated and the composite construction developed in connection therewith are well adapted to cheap manufacturing processes which can be carried out with conventional forming machinery such as punches, forming and shearing dies, press and rolling mechanism, and the like. Also, relatively small amounts of money are required to be invested in tooling up to make the rings, and a relatively small investment is required to be maintained at any one time as compared with corresponding costs in connection with the manufacture of cast iron rings.

While the particular forming steps illustrated have been shown in connection with a length or strip of sheet material, it is intended that such operations may be effected upon various other materials occurring in other forms, as in sheet form, or in a web or roll. The material itself may vary in cross section to present relatively thicker mid-portions as illustrated in the material 9 shown in Fig. '7; "Such a cross section may be utilized to secure "stronger web portions when folded in the manner indicated in Figs. 1-4, inclusive. Other means may be utilized to modify the character of ring structures as for example the use of a plurality of strips or sheets of material. The cutting or forming operations may be varied as for instance in the manner indicated in Fig. '7 in which alternately disposedslits or cuts l and II of substantially the same width throughout are employed in place of the openings shown in Figs. 2-and 3. Still other changes in extending portions of the material.

the'openings or cuts may be resorted to, as for example openings may be disposed diagonally or angularly of a strip of the material or in other ways. Also, the cutting or forming operations may be desired to be efiected at other stages of the method of making the ring, as after a sheet or strip of piston ring material has been folded or formed into either an intermediate or finished position, or at some other point. In addition, it may even be desired, in accordance with the invention, to utilize the cutting or forming operations to provide ring-forming portions completely severed from one another and adapted to be separately brought together, piece by piece, on some form of annular supporting structure.

Figs. 8-24, inclusive, relate to a number of modifications of the method just described.

With reference to that modified method included in Figs. 8-13, inclusive, l2 indicates a strip of material which may be formed in some suitable manner such as punching, as illustrated in Fig. 9, .to provide openings l3. Thereafter the blank iscut or formed with slits l4 and I5 alternately connecting with the openings I3 in substantially the same manner'as'has been described in connection with the methods of Figs. 1-4, inclusive.

It will be noted that the openings l3 are shorter in a direction transverse of the strip than the openings '2 earlier described. Inaccordance with the method, the material is'folded longitudinally and in such manner as to arrange the openings l3 so that they occur entirely in the vertically By this specific method ofcutting and folding, the segments l6 and I1 formed in the material are of a substantially uninterrupted extent radially and present a series of continuous top and bottom circumferential surfaces in the ring bodyas may be more clearly seen in Figs. 12 and 13.

This modified method is further illustrative of changes in the proportions of the openings ef fected which result in substantial differences in the ring surfaces attained thereby.

Still another modification of method has been illustrated in Figs. 14-19, inclusive, which consists in forming astrip l8 into a member having a cross section of open character such as the U- shaped construction l9 illustrated in Fig. 15. The folded strip is then subjected to a cutting operation as has been illustrated in Fig. 16 to form spaced-apart web portions 20. Thereafter other slits or openings of some type as indicated at 2| in Fig. 17 may be effected to form a ring 'ofsubstantially completed form as illustrated in Fig. 18, having a series of segments 22 and 23 arranged in contiguous relation to constitute circumferential edges in the manner described in connection with Figs. 4 and 5.

This procedure is intended to be illustrative of methods of forming piston rings in which a step or steps of folding sheet material precedes cutting or other forming operations. This type of method may be resorted to in connection with any of the modified methods already described or appearing hereinafter, or with other methods in which circumferential oil scraping edges are incorporated in a sheet metal piston ring body.

It is pointed out that in some instances, it may be-an advantage to first fold the sheet metal and thereafter apply cuts to the folded portions, as for instance where a plurality of cutting members of different types are simultaneously applied at opposite sides of the folded stock. Other advantages may be obtained from such a procedure.

In addition to those advantages obtained from changing the sequence of the folding operation, other novel changes may be derived from further modifying the folding operation in the manner illustrated in Figs. 20-24, inclusive, in which a strip 24 is treated to some type of forming operations as for example those indicated in Fig 21 and 22, to provide a blank of above described character having segments or crown portions 28 and 28, openings 21, webs 28, and cuts 29 and 88. Thereafter the step of folding the material longitudinally, to form circumferential edges, is modified by forming the webs 28 into a number of spaced-apart folds to effect a reversely folded structure as illustrated in Figs, 23 and 24. The reversely folded webs 28 are arranged in radially relieved relation with respect to the circumferential edges made up of the segments 28 and 28 so that these edges extend radially of the ring as in the product of earlier methods. As before, the points of folding of the webs 28 constitute the inner periphery of the ring and in this instance comprise two rows of spaced-apart folds. The reverseiy folded construction adds to the length of the webs 28 and thereby amplifies the vertical resiliency of the ring, increases its height, enlarges its oil passage area and effects other desirable changes in the ring.

Figs. 25-28, inclusive, illustrate another genera type of method of incorporating circumferential oil scraping edges in a ring body together with modifications thereto.

Referring to Figs. 25 and 26, numeral 3| denotes a strip of material formed with segments 32 at one edge thereof and also formed with slits 83 extending inwardly of the segments to facilitate bending of the strip. In this method the strip is folded transversely of itself to alternately arrange the segments at the top and bottom of an annular supporting structure with the segment occurring in contiguous relation to one another and extending beyond the supporting structure as illustrated in Fig. 26 to form circumferential scraping edge portions.

Figs, 2'7 and 28 illustrate a modification of the method just described in which folding of a strip,

transversely of itself, may again be modified, A

strip of material 34 is formed with oil holes 31 and segments 38 and 36 disposed along opposite edges thereof and in staggered relation. The formed material is folded transversely of itself and then formed into an annular body in which the lines of folding extend vertically of the ring instead of radially as in the preceding method just described. Thereafter the segments 35 are bent over to form an upper circumferential edge and r segments 36 are bent in an opposite direction to comprise a lower circumferential edge as illustrated in Fig. 28. This modification is particularly exemplary of folding the segments or formed portion out of the plane of the material from which it was fashioned and as before provides extending oil scraping edges integral with a supporting structure.

It will be observed that there have now been disclosed and described a number of methods of incorporating in ring bodies ring portions or segments which are adapted to constitute circumferential oil scraping edges. It is pointed out that a novel combination of cutting and folding operations has been devised to produce novel ring portions and ring functions. Attention is directed to the fact that there are produced cheap, light, eiflcient and durable oil ring structures, adapted to being manufactured from tool machinery whereby cheap and efiicient production may be attained. Advantageous oil conducting, resiliency, extensibility, durability, and ease of assembly have been combined in a unitary ring structure, and undesirable factors present in conventional oil control rings have-been reduced or eliminated.

While I have shown preferred embodiments of the invention it should be understood that various changes and modifications may be resorted to in keeping with he spirit of the invention as defined by the appended claim.

Having described my invention, I claim:

That improvement in methods of making oil control piston rings which comprises cutting spaced openings elongated transversely in a fiat strip of piston ring material at points intermediate the edges thereof and forming transversecuts through the opposite edge of the strip to connect with said openings, said transverse cuts being of less width than said openings to provide sealing portions o'ccurring alternately at opposite edges of the strip and intermediate supporting portions for the sealing portions, bending said supporting portions along two parallel lines of bending which extend longitudinally of the strip to arrange the sealing portions and parts of the supporting portions in spaced apart parallel relation such that the sealing portions at one edge of the strip are' located above points of eparation of two of the sealing portions at the other edge of the said strip and bending the supporting portions toward one another to provide a split ring body in which the supporting portions extend radially inward at the inner periphery thereof. THOMAS A. BOWERS. 

